1. Field of the Invention
This invention relates to novel polymer/polyisocyanate compositions that are reactive with active hydrogen organic compounds having two or more active hydrogen containing atoms per molecule to produce polyurethane products. The invention also relates to novel methods for making such compositions and to methods for making polyurethane products therefrom.
2. Description of the Prior Art
Compositions containing polymers of ethylenically unsaturated monomers in polyisocyanates are described in U.S. and foreign patents and patent publications. Such prior art compositions have found little, if any, use commercially because of any one of many difficulties notably instability, excessive particle size, or the inability when reacted with active hydrogen-containing compounds to provide improved properties, e.g., high modulus to the resulting polyurethanes in those cases where the polymers were dissolved in or reacted with the polyisocyanate. In those instances where dispersions of polymer in polyisocyanate did result the dispersions were relatively unstable and lacked sufficient usefulness in most modern techniques of polyurethane manufacture.
Polymer/polyol dispersions have been and currently are being used in the production of polyurethane products by mixing with polyisocyanates and other polyurethane-forming reagents and reacted to form the polyurethane product and serve as a convenient, efficient and economical means for improving resultant polyurethane properties. This procedure and the resulting polymer/polyol dispersions have been widely accepted by the polyurethane industry and continue to be extensively used throughout the industry.
As mentioned above prior attempts have been made to make polymer dispersions in polyisocyanates and to use such dispersions in the manufacture of polyurethanes by reaction with active hydrogen compounds. It is believed that these attempts have met with little or no commercial success for a variety of reasons. When dispersions were obtained pursuant to the prior art teachings they lacked adequate stability to be commercially feasible. The development of more sophisticated, higher speed and larger volume equipment, machines and systems for handling, mixing and reacting the polyurethane-forming ingredients have created the need for improvement in polymer/polyisocyanate, polymer/polyol and other dispersions used. The need for more stable dispersions has developed so that they can be stored until used without undergoing any significant settling or separation. Another criterion imposed by sophisticated equipment is the need for small particle sizes because large particles tend to damage the pumps employed in such equipment.
At one time there was not much concern for the seediness, viscosity or filterability of the polyurethane-forming reactants, i.e., the polymer/polyol and other dispersions in actual commercial practice. However, the state of the art of polyurethane production now has advanced to the point where these considerations are very important. There is now much concern with filterability, seediness, and viscosity because of the more sophisticated machine systems now in use for large volume production. Also, the prior art dispersions could not be made in highly stable condition with the relatively low molecular weight polyisocyanates, thus rendering the lower molecular weight materials less desirable than the higher molecular weight materials as a component of the dispersions. The lower molecular weight materials, however, are of value in those instances where low viscosity is essential and for foams, coatings, adhesives and some types of sealants.
The present invention provides highly stable and highly filterable polymer/polyisocyanate compositions which are low in, or substantially free of, seediness. It provides better dispersion stability than can be obtained by earlier procedures and/or eliminates or minimizes the expenses and hazards or difficulties accompanying some of the earlier techniques. The present invention also provides means for providing highly stable or reasonably stable polymer/polyisocyanate compositions having high polymer contents by using relatively small amounts of monomers copolymerizable with the acrylonitrile forming the polymer of said compositions and the production of polyurethanes containing higher amounts of polymer particles, e.g., when polymer/polyols are also used. It also permits a wider selection of polyisocyanates and polymer contents to be used in the manufacture of stable polymer/polyisocyanate compositions. It also permits the use of polyisocyanates of lower viscosities and higher polymer contents in the dispersion without impairing stability. These and other advantages are obtained by employing acrylonitrile as the sole ethylenically unsaturated monomer or, preferably, with small amounts of other ethylenically unsaturated monomers copolymerizable therewith to form a polymer in situ in a polyisocyanate, which, in the case of acrylonitrile homopolymers, consists essentially of a diarylalkylene diisocyanate, e.g., diphenylmethylene diisocyanate, in the presence of, or absence of its corresponding carbodiimide which is capable of forming a trifunctional cycloadduct therewith and other polyisocyanates based on diarylalkylene diisocyanate.
Nowhere in the prior art currently known to us is there any disclosure or suggestion of the discovery of the advantages of the present invention in the use of acrylonitrile without, or preferably with monomers copolymerizable therewith, to form dispersed polymer particles in situ in a polyisocyanate component consisting essentially of a diarylalkylene diisocyanate, ADI, or other polyisocyanates based on ADI.
British Pat. No. 1,447,273 discloses compositions of a polymer of an ethylenically unsaturated monomer, e.g., acrylonitrile, in an isocyanate. The compositions disclosed in the Examples of this patent lack stability and are not suitable for the production of good elastomers. In one instance (Example 9) a major amount of 4,4'-diphenylmethane diisocyanate (MDI) was used in the polyisocyanate component and a solid product was formed thus leading the skilled worker away from the use of increased amounts of MDI (compare with Example 8). Furthermore, British Pat. No. 1,447,274 by the same patentee acknowledges that the preparation of compositions according to the '273 British patent is not particularly successful when a crude isocyanate is used.
British Pat. No. 1,447,274 discloses the preparation of the polymers of one or more ethylenically unsaturated monomers in an inert solvent, adding the polyisocyanate to the resulting polymer solution and distilling off the solvent to form a dispersion of polymer in the polyisocyanate which in one Example (Example 2) Solidifed on standing.
Japanese Patent Publication No. JA 50,149,795 discloses polymer-containing polyisocyanates made by heating certain vinyl monomers and a free radical catalyst in diphenylmethane diisocyanate. Japanese Patent Publication No. J 54/050,091 discloses urethane-polymer emulsions or dispersions essentially free of isocyanate groups suitable for making paints made by polymerizing vinyl monomers in a toluene-diluted polyurethane. There is no disclosure of forming a dispersion of an acrylonitrile polymer or copolymer in a polyisocyanate. No working Example in these publications utilizes acrylonitrile.
U.S. Pat. No. 3,654,106 discloses the formation of vinyl polymers grafted onto polyisocyanates to form telomers which are dissolved in the polyisocyanate when an excess of polyisocyanate is used.
U.S. Pat. No. 3,968,089 discloses the polymerization of ethylenically unsaturated monomers in a polyol-polyisocyanate prepolymer. Published West German patent application 2,609,355, published Aug. 9, 1977 (Derwent 65225Y/37 DT 2609355) has a similar disclosure.
U.S. Pat. No. 4,122,049 discloses the formation of sedimenting dispersions of aminoplasts in polyisocyanates by reacting a carbonyl compound, such as formaldehyde, with a nitrogen compound, such as urea, in situ in a polyisocyanate. The dispersions produced by the teachings of this patent are sedimenting which is the opposite of the stable dispersions of this invention.
U.S. Pat. No. 3,422,165 discloses polymer/polyisocyanate complex compositions formed by polymerizing ethylenically unsaturated monomers such as acrylonitrile in polyisocyanates such as tolylene diisocyanate ans also discloses the production of polyurethanes from such complex compositions. While the subject matter of this patent broadly encompasses part of our invention, there is no specific disclosure relating to the production of stable dispersions of polyacrylonitrile (or copolymers or terpolymers of acrylonitrile and other ethylenically unsaturated monomers) in polyisocyanates consisting essentially of a diarylalkylene diisocyanate, or its polymeric form, in the presence or absence of its corresponding carbodiimide and its trifunctional trimeric cycloadduct, derivatives thereof or mixtures of any two or more such polyisocyanates or derivatives.